The present invention relates to seals for sealing relatively rotating machine parts and, more particularly, a slide ring seal of the type comprising a slide ring having a central axis and a circumferential face, a tubular sleeve member formed of a bellows which encircles and engages at least a portion of the circumferential face of the slide ring and an adhering part constituting an integral continuation of the bellows and extending in a generally axial direction away from the slide ring. The slide ring seal further comprises an approximately conically wound compression spring positioned within the tubular sleeve member in the zone of the adhering part and the bellows.
A slide ring seal of this type is known from German Offenlegungschrift (Application Published Without Examination) No. 2,921,669. A support housing provided in the zone of the inner circumferential face of the adhering part serves to radially shape the latter. A cylindrical compression spring extends axially between the support housing and the bellows. In the zone of the bellows, the slide ring is radially clamped in such a manner that the diameter of the bellows is larger than the inner diameter of the spring turns.
A slide ring seal of similar construction as described above is shown in British Pat. No. 888,118. This structure, however, has no support housing; its function is assumed by a compression spring which includes an initial cylindrical portion and a stepped, approximately conical portion. The spring turn of smallest diameter engages a groove formed in the bellows axially adjacent the slide ring. Apart from the complex shape of the bellows, a transmission of torque from slide ring to the adhering part is poor, since the spring merely carries out guiding functions.
Further, German Gebrauchsmuster (Utility Model) No. 1,858,504 discloses a slide ring seal in which the end turns of the cylindrical spring surround the bellows and further, on one side the spring exerts a radial pressure on the slide ring and, when installed, it exerts, on the other side, a radial pressure on the shaft with the intermediary of the bellows. Again, the diameter of the bellows is larger than the inner diameter of the spring turns. In this construction, the bellows is radially so thick that the spring cannot exert any radial force on the shaft; rather, this force is applied by the bellows itself since in seals of this type the inner diameter of the elastomer member is, as a rule, designed to be smaller than the diameter of the shaft. Thus, the elastomer member expands when it is axially pressed onto the shaft and circumferentially engages the same under internal radial tension.